Rotary heel-seat cutter.



A. L. GREEN.

ROTARY HEEL SEAT CUTTER.

APPLICATION man FEB. 6. 1915.

Patented July 6, 1915.

IE a I IE ST L T FFIQ.

ALONZO Il- GREEN, OF LYNN, MASSACHUSETTS, ASSIGNOB TO HAMEL SHOEMACHINERY COMPANY, OF LYNN, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

ROTARY HEEL-SEAT CUTTER.

Specification of Letters Patent.

Patented July 6, 1915.

Application filed February 6, 1915. Serial No. 6,657.

To all whom it may concern:

Be it known that I, ALoNzo L. GREEN, a citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts, have inventeda certain new and useful Improvement in Rotary Heel-Seat Cutters, ofwhich the following is a specification, reference being had therein tothe accompanying drawings.

My invention has for its object a new and improved rotary heel seatcutter to be employed in the manufacture of shoes, and particularly fortrimming from the edge of the heel seat and heel the bur which remainsafter the heel has been trimmed. Rotary cutters for this purpose are oldand well known in this art, and consist of a series of teeth or bladessecured to a hub and separated from each other by slots. 7

As previously constructed and employed commercially each of the bladesor teeth has been thicker at the front than at the back growinggradually thinner toward the rear of the blade, this being the result ofthe fact that the edges of the interior surfaces of the blades are arcsof a circle formed about the center of rotation of the cutter and of thefact that the toe or front point of each tooth projects farther from thecenter than the heel so as to give the requisite clearance. It has beenfound that cutters, when thus c0nstructed, are objectionable because thegreater thickness at the point of the blade makes it necessary to grindthe blade so long that the metal is heated and the temper is drawn. Itresults that the cutter will not hold an edge and requires frequentgrinding. After the cutter has been ground a considerable number oftimes and has been ground down to the point near the heel where theblade is comparatively thin, a small amount of grinding will. form theproper edge on the cutter and the temper is not drawn. The cutter thenholds an edge well and is altogether more satisfactory.

I am aware that an attempt has also been made to produce cutters havinga uniform thickness of the blades of the teeth by forming their exteriorand interior surfaces in concentric circles and then bending each bladeoutwardly sufficiently to give the requisite clearance. In so doing thestructure of the metal in the spoke at the point where the bending takesplace is changed; also, a similar change takes place in a portion of theblade adjacent the spoke and a minute depression is formed at thispoint, giving to the blade an irregular slope toward the heel of theblade. I also find that there is a tendency for the blade to be twistedby bending. Such cutters have proved altogether unsatisfactory in actualuse. I am not entirely certain why this is the case, but I be lieve itto be due to the'fact that the respective blades are not given the sameamount of clearance and also because the irregular curve of the bladeproduces friction and consequent heating when the cutter is in useparticularly when the clearance has been reduced by frequent grinding.It is also unsatisfactory because a steel must be used which will permitthis procedure and such steel is softer and will not take so good anedge.

My present invention therefore has for its object a rotary heel seatcutter so constructed as to obviate the foregoing objections and havingteeth of uniform thickness from front to rear thereby requiring auniform and minimum amount of grinding and holding an edge as Well whenthe teeth are of full length as when they have been ground back towardthe heel. The metal composing the spokes and blade is not bent but is inits original condition, its structure in the finished cutter beinguniform with that of the rest of the cutter, and therefore the metal maybe of the kind best adapted to take and hold an edge. Also the exteriorsurface of the blade is perfectly smooth and true and free fromdepressions.

The invention will be fully understood from the following descriptiontaken in connection with the accompanying drawings, and the novelfeatures thereof are pointed out and clearly defined in the claims atthe close of this specification.

In the drawings, Figure 1 is a side elevation of a rotary knifeembodying my invention. Fig. 2 is a section on line 2-2 Fig. 1, lookingin the direction of the arrows. Fig. 3 is a front elevation.

Referring to the drawings, at A is shown the hub, and at B, C, D, E, Fand G the teeth. The number of the teeth is immaterial. Each tooth iscomposed of a spoke 11 and a blade 12. lhe front end or toe of the bladeforms the cutting surface and is designated 13 and the rear end or heelis designated 14.

At is indicated the flange which rests against the guard (not shown) bywhich the knife is guided in the crease between the heel seat and theupper of the shoe. The space between each pair of teeth is formed bycutting a slot at one edge of which is substantially tangent to the hubA. Thecutting edge is formed by grinding the surface 16 along the linewhich is also substantially tangent to the hub. It will be seen bycarefully comparing the position of the point 13 and the point 14 thatthe cutting edge 13 of one toothis at a greater distance from the centerthan is the heel of the adjacent tooth. In other words, a suitableclearance is given each blade. It will also be seen that .the thicknessof the blade on the side edge is uniform from the point 13 to the point1 1, or to state the matterdifierently the curve formed by the line Z)(seeFig. 1) which represents the outer surface of the tooth isconcentric With the curve 0 which represents the inner surface of thetooth. It will be understood of course that both of these curves arespirals being formed by a cutting tool which is given a movementradially from the center of rotation of the blank. two curves Z) and care therefore conveniently referred to as portions of spirals.

The cutter is formed from a suitable blank of steel by a speciallyconstructed lathe or machine in which the cutting tool is given asuitable motion radially of the center of rotation of the blank, themovement of the cutting tool being the same when the curve 6 is formedas when the curve 0 is formed.

It will be seen that the cutter as thus con- Copies of this patent maybe obtained for five cents each, by addressing the The i doing the metalof which the blade is com posed is not heated, the temper is not drawn,and the finished cutter retains its'cutting edge. Furthermore, the timerequired to grind the cutter is reduced to about one half that requiredto grind a cutter of the type having blades of diflerent thickness fromthe toe to the heel of the blade.

I also find that all heating due to friction with the heel when in useis done away with,

the blades having a smooth true outer surface and equal clearance. AlsoI can make these cutters of the quality of steel best adapted to takeand hold a cutting edge.

What I claim is:

1. The improved heel'seat cutter which comprises a hub, spokesprojecting from the hub, and blades on the said spokes, each of saidblades having the point or cutting edge at a greater distance from thecenter of rotation than the heel, and said blade being of substantiallyuniform thickness from the cutting edge to the heel ofthe blade, thestructure of the metal of which said spokes and blades are composedbeing uniform throughout.

2. The improved heel seat cutter which comprises a hub, spokesprojectingfrom the hub, and blades on said spokes, each of said bladeshaving the point of cutting edge at a greater distance from the centerof rotation than the heel, said blade being of substan tially uniformthickness from the cutting.

edge to the heel of the blade, the curves formed by the inner and outeredges of said blades being portions of concentric spirals.

In testimony whereof I afliX my signature, in presence of two witnesses.

ALONZO L. GREEN.

WVitnesses 7 Gnoncn P. DIKE, ALICE H. MORRISON.

Commissioner of Patents,

Washington, D. C.

